Hull structure of nonmetallic material

Abstract: A hull structure of nonmetallic material, in particular of a reinforced plastics material, for boats, ships, minesweepers and the like, comprises a preferably one-piece shell (1) and at least one deck (2, 2') and has a plurality of ribs (3) which are distributed along the length of the hull and extend across the corresponding transverse section of said shell (1) and a plurality of transverse members (4, 4') (known as beams) which extend directly underneath the deck (2, 2'). In order to give the hull greater structural strength and make it lighter, the invention provides that each transverse rib (3) joined to the shell (1) is connected (103, 203) to a corresponding transverse member (4, 4') joined to the deck (2, 2') and to continuous fore and aft members (15) (girders) passing in the manner of bulkheads, so as to form a single one-piece frame with the keel member. The invention achieves the aforesaid object to a still greater degree by means of additional improvements.

Description: The invention relates to a hull structure of nonmetallic material, in particular of a reinforced plastics material, for boats, ships, minesweeper and the like, which structure comprises a preferably one-piece shell and at least one deck and has a plurality of ribs which are distributed along the length of the hull and extend across the corresponding transverse section of said shell, and a plurality of transverse beam members which extend directly underneath the deck and in which hull structure, according to the preamble of claim 1: a) in each transverse rib joined to the shell is connected to a corresponding transverse beam member joined to the deck so as to form a single one-piece frame, with fore and aft members situated underneath the forecastle deck, upper deck and 'tween deck, b) the transverse ribs extend across the entire transverse section of the shell and are connected at their free upper ends to the members joined to the upper deck, c) there are a plurality of decks one above the other, to each of which a plurality of transverse members are joined, one transverse member of each respective deck being connected to each individual tranverse rib. A hull structure of this kind is known from the document: Transactions of the SNAME, Vol. 73, 1965, pages 428-430; K. Spaulding "Fiberglass Reinforeced Plastic Minesweepers", Figures 7, 8 and 9.Engine rooms bounded by vertical bulkheads wherein the engines are suspended by annular engine cradles and fixed to the bulkheads and to the deck are per se known from the document GB-A-2161773, in which are shown also annular beams surrounding a deck opening. The hull structure known from the document GB-A-2161773 is however a metallic structure and constructively different from the hull structure according to the preamble of claim 1.The object of the invention is to provide a hull structure of the above-described type, which by means of an extremely simple structural design has greater structural strength and less weight without affecting the qualities of the hull made of nonmetallic material, in particular of reinforced plastics materials.The invention achieves the above objects with a hull structure of the above described type, characterized - according to the characterizing part of claim 1 - by the combination of the following features: d) the hull structure comprises an engine room which is bounded by vertical bulkheads, while each engine is suspended by an annular engine cradle fixed to the bulkheads and to a deck overhead which forms the upper surface of the engine room, e) each engine cradle is made in one piece and consists of at least one, and preferably two, annular one-piece frames that are positioned vertically side by side parallel with each other and at a certain distance from each other, each annular frame being fixed separately to the bulkheads and to the deck, f) the annular frames of each engine cradle are connected to each other by one or more crosspieces along their bottommost and/or topmost sides, g) the length of the crosspieces is such as also to connect together all the engine cradles of the engines provided, h) the annular frames and the crosspieces are connected in such a way as to form a single one-piece engine seating resembling a cage, i) the annular frames are complementary in shape to the section of the engine room taken through the vertical plane joining the bulkheads, and in particular are essentially rectangular or quadrilateral. The above combination results in a hull having greater structural strength while at the same time its weight, and therefore also materials and costs, are limited. The arrangements according to the invention are furthermore easy and inexpensive to put into practice and the outlay in terms of time and manufacture is not great. The invention also covers other features which further improve the above-described hull structure: these are the subject of the subclaims. The special features of the invention and the advantages derived therefrom are described in further detail in the description of a preferred embodiment, illustrated by way of a non-restrictive example in the accompanying drawings, in which: Fig. 1 is a view in transverse section of the hull structure according to the invention at the location of the engine room. Fig. 2 is a sectional view taken through a vertical fore and aft plane of the hull structure and of an engine cradle according to the invention. Fig. 3 is a section taken through a horizontal fore and aft plane of the hull structure and of the engine cradle. Fig. 4 is a section taken through a fore and aft vertical plane of the hull at the location of the tank room. Fig. 5 is a view in transverse section of the tank room according to Fig. 4. A hull structure of nonmetallic material, in particular of a reinforced plastics material (Fig. 1) comprises a shell 1 and at least one deck 2. The skin of the shell 1 and deck 2 is comparatively thin. Attached to the internal surface of the shell 1 is a plurality of ribs 3 which extend across the internal transverse section of the shell 1. The transverse ribs 3 are distributed at intervals and parallel with each other along the length of the hull and extend as far as the top edge where the shell 1 joins an upper deck 2. At this point each transverse rib 3 is connected at its top ends 103 to the ends of a transverse member 4, known as a beam, which extends directly underneath the corresponding deck 2. The hull structure may also comprise a plurality of decks one above the other. Fig. 1 shows an intermediate deck 2' which forms the upper surface of the engine room. Joined to the intermediate deck 2' is a plurality of transverse members 4'. The transverse members 4' are connected likewise to the corresponding transverse ribs 3 at an intermediate point 203 thereof. In this case, however, the transverse members 4' illustrated in Fig. 1 are interrupted in the middle of the structure to allow for openings for installing or removing machinery. Each transverse rib 3 is connected to its associated transverse members 4, 4' in such a way as to form a one-piece annular frame which therefore extends around the inside of the transverse section of the hull. The transverse members 4, 4' of the annular frames intersect, and connect with, a plurality of fore and aft beams 15, 15' on which the decks are supported, while the transverse ribs connect at their middle with the keel member 16, thereby forming a one-piece load-bearing skeleton for the skin of the decks and of the shell. The ribs 3 and the beams 4, 4' are likewise made of a nonmetallic material, in particular a reinforced plastics material, and are fixed to the shell 1 and to the deck 2, 2'. With reference to Figs. 1 to 3, the engine room is bounded by two opposite transverse bulkheads 5, 5' which are vertical and parallel to each other and are fixed to the hull structure, in particular to the shell 1 and to the intermediate deck 2'. Fixed in a suspended position to said two bulkheads 5, 5' and to the deck 2' is a cradle 6 for an engine. In the example illustrated there are two engines, each of which is carried by its own engine cradle 6, 6'. The cradles 6, 6' are side by side and parallel with each other. The engine cradles 6, 6' consist of one or more - in particular two - annular one-piece frames 106 located side by side at a certain distance from each other and in form are basically rectangular or quadrilateral. Said frames 106 are positioned vertically and are oriented in the fore and aft direction of the hull (Fig. 2). Their bottommost side stands a certain distance off the underlying shell 1. The annular frames 106 of each engine cradle 6, 6.' are fixed separately to the bulkheads 5, 5' and to the intermediate deck 2'. Each engine is designed to rest on the lower members of the annular cradles 6,6', inside these cradles. The annular frames 106 are formed by a tubular, preferably trapezoidal, section which becomes broader towards the external periphery, where both its sides have a lateral flange 306 that is preferably continuous. The tubular section may be hollow or internally reinforced. As can be seen in Figs. 1 and 2, at about the height of the horizontal mid plane of the engine cradles 6, 6', and preferably slightly above this, the tubular sections become laterally narrower 206 in cross section. Therefore the cross section of the annular frames 106 is greater at the bottom than at the top. The annular frames 106 of each engine cradle 6, 6' are connected together at the lower members by crosspieces 7. The crosspieces 7 may continue beyond the engine cradles 6, 6' of each engine so as to connect together the cradles 6, 6' of all the engines provided. In the same way the upper members of the annular frames 106 and/or the annular engine cradles 6, 6' may optionally be connected together. The crosspieces 7 are at the same level as the bottommost sides of the engine cradles 6, 6' and flush with them above the bottom of the shell 1. They may be formed by sections similar to those used for the cradles themselves. The annular frames 106 and the crosspieces 7 are preferably connected together in such a way as to form a one-piece cradle seating resembling a cage which is thus extremely light but has great structural strength and enables the advantages of suspended engine support to be exploited. In a similar way to the construction of the engine cradles 6, 6', the transverse ribs 3 and transverse members 4, 4' making up the one-piece frames of the hull may also be formed by tubular sections of similar cross-sectional form. Another feature is that the hull structure is also provided with tanks 8 for fuel, water or other fluids. The tanks 8 consist of a tubular, preferably cylindrical body whose fore and aft ends are open. At these fore and aft ends the tanks 8 have a peripheral flange 108 by which they are hermetically fastened to two opposite vertical bulkheads 9 of the hull structure which thus form the ends of the tubular body. The tanks 8 are supported by the bulkheads 9 a certain distance off the bottom of the tank room, and in particular off the shell 1. At one or more intermediate points, in particular at two intermediate points set apart axially from each other, the tubular bodies of the tanks 8 also rest on transverse ribs 10 with elastic suspensions 11 interposed between the tanks 8 and the ribs 10. These elastic suspensions 11 may be made from any material, e.g. an expanded plastics material, rubber, or the like. In the particular form shown in Figs. 4 and 5, the ribs 10 consist of the bottommost edge of windows 12 let into intermediate vertical walls 13. Said intermediate walls 13 are fixed to the ribs of the bottom of the tank room, and the ribs in turn are connected to the shell 1. In particular, said intermediate walls 13 connect together the bottom of the tank room and its upper surface or "'tween deck" 14 above the latter. The windows 12 are open up to the topmost edge of the intermediate walls 13, while the bottommost edge thereof, which forms the transverse rib 10 on which the corresponding tank 8 rests, is essentially complementary in shape to the transverse section of the tubular body of that tank. In conclusion, the strong structure of the hull is to be regarded as consisting in the fore and aft structure of the continuous members running underneath the decks, in the continuous transverse ribs running in a closed hoop around the hull and in the keel. The resulting structural framework ensures the flexural strength of the upper deck and forecastle deck, while at the keel the strength is ensured by the structure of the keel itself connected to the fore and aft members of the 'tween deck by the transverse ribs and by the intermediate walls.

Claims: Hull structure of nonmetallic material, in particular of a reinforced plastics material, for boats, ships, minesweeper and the like, which structure comprises a preferably one-piece shell (1) and at least one deck (2, 2') and has a plurality of ribs (3) which are distributed along the length of the hull and extend across the corresponding transverse section of said shell (1), and a plurality of transverse beam members (4, 4') which extend directly underneath the deck (2, 2'), and in which hull structure: a) in each transverse rib (3) joined to the shell (1) is connected (103, 203) to a corresponding transverse beam member (4, 4') joined to the deck (2, 2') so as to form a single one-piece frame, with fore and aft members (15, 15') situated underneath the forecastle deck, upper deck and tween deck, b) the transverse ribs (3) extend across the entire transverse section of the shell (1) and are connected at their free upper ends (103) to the members (4) joined to the upper deck (2), c) there are a plurality of decks (2, 2') one above the other, to each of which a plurality of transverse members (4, 4') are joined, one transverse member (4, 4') of each respective deck (2, 2') being connected to each individual tranverse rib (3), characterized by the combination of the following features: d) the hull structure comprises an engine room which is bounded by vertical bulkheads (5, 5'), while each engine is suspended by an annular engine cradle (6, 6') fixed to the bulkheads (5, 5') and to a deck (2') overhead which forms the upper surface of the engine room, e) each engine cradle (6, 6') is made in one piece and consists of at least one, and preferably two, annular one-piece frames (106) that are positioned vertically side by side parallel with each other and at a certain distance from each other, each annular frame (106) being fixed separately to the bulkheads (5, 5') and to the deck (2'), f) the annular frames (106) of each engine cradle (6, 6') are connected to each other by one or more crosspieces (7) along their bottommost and/or topmost sides, g) the length of the crosspieces (7) is such as also to connect together all the engine cradles (6, 6') of the engines provided, h) the annular frames (106) and the crosspieces (7) are connected in such a way as to form a single one-piece engine seating resembling a cage, i) the annular frames (106) are complementary in shape to the section of the engine room taken through the vertical plane joining the bulkheads (5, 5'), and in particular are essentially rectangular or quadrilateral. Hull structure according to claim 1, characterized in that the annular frames (106) are oriented in the fore and aft direction of the hull. Hull structure according to one or more of the preceding claims, characterized in that the annular frames (106), the crosspieces (7) and optionally also the transverse ribs (3) and the transverse members (4, 4') may be made of tubular sections. Hull structure according to Claim 3, characterized in that the section is trapezoidal in section becoming broader towards the external periphery or that side where it joins the corresponding part of the shell (1) or deck (2, 2') and provided with at least one and preferably two continuous transverse lateral flanges (306) along said side. Hull structure according to one or more of the preceding claims, characterized in that that part of the annular frames (106) above approximately the horizontal mid plane of the engine cradles (6, 6') is smaller in cross section than that below it. Hull structure according to one or more of the preceding claims, characterized in that it comprises a plurality of tanks (8) for the diesel oil, water or other fluids, which tanks are fixed (108) by means of their fore and aft ends to corresponding bulkheads (9) of the hull structure in a suspended position above a bottom wall or above the shell (1) and also rest on the hull structure (10) at intermediate points via elastic suspensions (11). Hull structure according to Claim 6, characterized in that the elastic suspensions (11) may be made from any material, e.g. rubber, an expanded plastics material, or the like. Hull structure according to Claim 6 or 7, characterized in that the tanks (8) rest via elastic suspensions (11) on intermediate transverse ribs (10) between the bulkheads. Hull structure according to Claim 8, characterized in that the intermediate transverse ribs (10) consist of the bottommost edge of a window (12) housing the corresponding tank (8) and formed in a vertical intermediate wall (13) fixed to the hull structure itself, for example to the shell (1). Hull structure according to Claim 9, characterized in that the intermediate walls (13) connect together a bottom wall (1) of the tank room and an upper surface ('tween deck) (14) of said room, in particular the rib of the bottom (1) and a 'tween deck skin (14). Hull structure according to Claim 9 or Claim 10, characterized in that the windows (12) in which the tanks are housed are open up to the topmost edge of the corresponding intermediate wall (13). Hull structure according to one or more of the preceding claims, characterized in that the outer skins of the bottom and the superstructures are supported by transverse frames (3) only, with no common internal reinforcements.

Inventors: GUZZO GIOVANNI DR, MARCHETTI GIORGIO, GUZZO, GIOVANNI, DR., MARCHETTI, GIORGIO, GUZZO, GIOVANNI, DR., C/O INTERMARINE S.P.S., MARCHETTI, GIORGIO, C/O INTERMARINE S.P.S.
Applicants: INTERMARINE SPA, INTERMARINE S.P.A.
Application year: 1994
Main classification: B63B5
IPC codes: B63B5, B63B11, B63H21